SR-72, a Hypersonic Drone is Positioned to be the Successor of SR-71 ‘BlackBird’

The Skunk WorksSR-72 design – a hypersonic unmanned aircraft developed to execute Intelligence, Surveillance and Reconnaissance and strike missions at speeds up to Mach 6. Such an aircraft, coupled with hypersonic missiles, could penetrate denied airspace and strike at nearly any location across a continent in less than an hour. Photo: Lockheed Martin

Lockheed Martin broke silence today about the development of an unmanned hypersonic aircraft it is proposing for future reconnaissance and long-range strike missions. The company said it is ready to embark on the development of the SR-72 hypersonic unmanned aircraft that could enter service with the U.S. Air Force in 2030.

The proposed drone is positioned the follow-on to the Air Forces’ fastest known strategic reconnaissance aircraft – Mach 3 SR-71 ‘BlackBird’, developed by the legendary designer Clarence “Kelly” Johnson, the chief designer of the Lockheed skunk works in the early 1960s . Envisioned as an unmanned aircraft, the SR-72 would fly at speeds up to Mach 6, or six times the speed of sound. At this speed, the aircraft would be so fast, an adversary would have no time to react or hide.

Turbine Based Combined Cycle Propulsion

An SR-72 could be operational by 2030. For the past several years, Lockheed MartinSkunk Works has been working with Aerojet Rocketdyne to develop a method to integrate an off-the-shelf turbine with a supersonic combustion ramjet air breathing jet engine to power the aircraft from standstill to Mach 6.

The turbine based combined cycle propulsion means the turbine is combined with a ramjet to enable operation form static to hypersonic speeds of Mach 5+. At the turbine stage thrust is provided by the turbine engine from takeoff up to about Mach 3, where the ramjet kicks in, accelerating the aircraft up to hypersonic speeds. The turbine engine and ramjet are fed through a single inlet nozzle to significantly reduce drag.

The result is the SR-72 that Aviation Week has dubbed “son of Blackbird,” and integrated engine and airframe that is optimized at the system level for high performance and affordability. “Conceived as a solution to the proliferation of mobile weapons platforms, which can be concealed from satellites, the jet would fly so fast that adversaries would not be able to react in time to hide a mobile target.” Aviation Week writer Guy Norris said.

Lockheed Martin said it is ready to embark on the development of the new hypersonic drone. The SR-72’s design incorporates lessons learned from the HTV-2, which flew to a top speed of Mach 20, or 13,000 mph, with a surface temperature of 3500°F.

According to Brad Leland, Lockheed Martin program manager, Hypersonics, a hypersonic aircraft will be a ‘game changer’. “Hypersonic aircraft, coupled with hypersonic missiles, could penetrate denied airspace and strike at nearly any location across a continent in less than an hour,” said Leland. “Speed is the next aviation advancement to counter emerging threats in the next several decades. The technology would be a game-changer in theater, similar to how stealth is changing the battlespace today.”

SR-72 is not the first hypersonic Skunk Works aircraft. In partnership with the Defense Advanced Research Projects Agency, engineers developed the rocket-launched Falcon Hypersonic Technology Vehicle 2 (HTV-2). The HTV-2 research and development project was designed to collect data on three technical challenges of hypersonic flight: aerodynamics; aerothermal effects; and guidance, navigation and control.

The Skunk Works SR-72 design – a hypersonic aircraft developed to execute Intelligence, Surveillance and Reconnaissance and strike missions at speeds up to Mach 6. Photo: Lockheed Martin